1. Field of the Invention
The field of this invention is medical extraction devices, particularly such devices which are used to endoscopically remove foreign bodies from a patient.
2. Description of the Prior Art
In the medical field of gastroenterology, extraction devices are commonly used to endoscopically incise and/or grasp and remove foreign bodies from a patient. For example, a wire basket stone extractor might be used to extract gallstones from the bile duct of a patient. In such an operation, the stone extractor would be advanced through an endoscope, with its wire basket retracted within a retaining cannula. Once advanced, the wire basket would then be extended out of the retaining cannula, with the basket wires opening up into their pre-formed basket configuration. The basket is then manipulated to grasp and remove the gallstones from the patient.
The wire material used in prior art wire basket stone extractors and the like has most commonly been either monofilament or stranded stainless steel wire, and has generally been found to be satisfactory for the purpose intended. The stainless steel wire retains its pre-formed orientation, and returns to its basket configuration when extended from its retaining cannula, even after repeated use. After extended periods of non-use or after long-term repeated use, however, these wire baskets slowly tend to lose their pre-formed orientation, and eventually need to be replaced. The medical art in this area would benefit from an improved extraction device which holds its designed orientation longer and more precisely, and which therefore has to be replaced less frequently.